PDBsum entry 2p8o

Hydrolase

PDB id: 2p8o

Contents

Protein chains

131 a.a. *

95 a.a. *

Ligands

CYS-GLY-VAL-PRO-ALA-ILE-GLN-PRO-VAL-LEU

SO4

BVA

Waters ×207

* Residue conservation analysis

PDB id:

2p8o

Name:

Hydrolase

Title:

Crystal structure of a benzohydroxamic acid/vanadate complex bound to chymotrypsin a

Structure:

Chymotrypsin a chain a. Chain: a. Chymotrypsin a chain b. Chain: b. Chymotrypsin a chain c. Chain: c. Ec: 3.4.21.1

Source:

Bos taurus. Cattle. Organism_taxid: 9913. Organism_taxid: 9913

Resolution:

1.50Å R-factor: 0.197 R-free: 0.243

Authors:

A.Moulin,J.H.Bell,R.F.Pratt,D.Ringe

Key ref:

A.Moulin et al. (2007). Inhibition of chymotrypsin by a complex of ortho-vanadate and benzohydroxamic acid: structure of the inert complex and its mechanistic interpretation. Biochemistry, 46, 5982-5990. PubMed id: 17469803 DOI: 10.1021/bi6025209

Date:

22-Mar-07 Release date: 08-May-07

Protein chain

P00766  (CTRA_BOVIN) -  Chymotrypsinogen A from Bos taurus

Seq: 245 a.a.

Struc: 131 a.a.

Protein chain

P00766  (CTRA_BOVIN) -  Chymotrypsinogen A from Bos taurus

Seq: 245 a.a.

Struc: 95 a.a.

Enzyme reactions

• Enzyme class: Chains B, C: E.C.3.4.21.1 - chymotrypsin.
• Reaction: Preferential cleavage: Tyr-|-Xaa, Trp-|-Xaa, Phe-|-Xaa, Leu-|-Xaa.

DOI no: 10.1021/bi6025209

Biochemistry 46:5982-5990 (2007)

PubMed id: 17469803

Inhibition of chymotrypsin by a complex of ortho-vanadate and benzohydroxamic acid: structure of the inert complex and its mechanistic interpretation.

A.Moulin, J.H.Bell, R.F.Pratt, D.Ringe.

ABSTRACT

Serine proteases, like serine beta-lactamases, are rapidly and covalently inhibited by suitably designed phosph(on)ates. The active sites of these enzymes must, therefore, be able to stabilize the pentacoordinated transition states of phosphyl transfer reactions as well as the tetrahedral transition states of acyl transfers. It follows that these enzymes should also be inhibited by molecules capable of generating inert pentacoordinated species. We (J.H.B. and R.F.P.) have previously shown that these enzymes are, in fact, rapidly and reversibly inhibited by 1:1 complexes of vanadate and hydroxamic acids. In this paper, we present the first crystal structure of an acyl transferase inhibited by vanadate. The complex of vanadate and benzohydroxamic acid is a competitive inhibitor of alpha-chymotrypsin with a KI value of 16 muM. In the structure, obtained at a resolution of 1.5 A, the protein is conformationally little different from the apoenzyme. The vanadium, in a distorted octahedral ligand field, is covalently bound to the active site serine oxygen group. One oxgen ligand, presumably anionic, is located in the oxyanion hole. Another is directed roughly in the direction of the acyl transfer leaving group, and a third in the direction of the S2 site. The hydroxamate is bound to vanadium through the hydroxyl oxygen and also, more weakly, through the carbonyl group, to form a five-membered chelate ring. The effect of this chelation is to place the phenyl group of the inhibitor into the important S1 specificity site. The hydroxamate oxygen is directed in line away from the Ser195 Ogamma, approximating the direction of departure of a leaving group in phosphyl transfer. The entire complex can be seen as a reasonable mimic of a phosphyl transfer transition state where the leaving group is extended into the S1 site.